Abstract
Abstract: :
Purpose: The ocular lens grows throughout the life of an organism, yet the lens does not develop tumors. We considered that lens progenitor cells could reside outside the lens capsule in the adjacent ciliary body. To address this hypothesis experimentally, we asked whether cells external to the lens capsule contribute to the growing lens. Methods: Eyes were dissected from 16–day green fluorescence protein (GFP)–positive (Nagy strain) mouse embryos and non–GFP littermates and secured in 0.8% agarose. The lenses of GFP positive eyes were removed through an incision in the posterior retina. Intact GFP negative lenses were placed into the vacated GFP positive lens sphere. Eyes were maintained for 72 hours in medium 199 with 20% NBCS, and PSF. The cultured eyes were fixed in 4% paraformaldehyde and examined using an Olympus stereo fluorescence microscope with a GFP filter. Images were captured with a Q–Imaging cooled digital camera. Results: GFP positive cells were associated with the transplanted GFP negative lenses in approximately 10% of the cultured eyes. GFP positive cells were distributed singly and in small groups on the lenses. Many cells had a migratory phenotype. Conclusions: Cells external to the lens capsule migrated to the lens. Extracapsular cells may be the progenitors of lens epithelial and fiber cells. Pigment within the ciliary body may provide protection from UV damage for lens progenitor cells. A dearth of lens tumors may be explained by the extracapsular location of early stage lens progenitor cells.
Keywords: microscopy: light/fluorescence/immunohistochemistry